Service Tap

[hotline]

I have a 1200 amp 3 phase 480 volt service MDP (WITH NO MAIN SWITCH)
They are using only (5) five fused switches in this panel.
The main lugs have space for (4) four 750 Kcmil wires and (3) three are used by the incoming feeders. (3) Three sets of 600?s
The next available over current device would be the 13,800 volt pole mounted transformer fusing.
The power company pole mounted transformers are (3) each; 100 KVA 1 phase units. The 13,800 volt fusing size is unknown but only protects this set of transformers.

Can I use the open lug on the MDP to make a feeder tap on the existing service with 350 Kcmil?
Is this discussed in the code? Where?
CE

 

[infinity]

Is there really such a thing as a service tap?

 

[augie47]

Is there really such a thing as a service tap?

Good question. Can we still call it a "tap" and simply say it's a "tap" which is not governed by Art 240 ?
Perhaps a "reduced size service extension"
To me, the definition in Art 240, by starting out with "as used in this Article" addressed "taps" that fall under Art 240 but perhaps does not preclude us from using the word "tap" for a connection to a service. Just a word game.

Call it a "kratzjammer" connection or whatever. What you propose would be legal if installed with the parameters of Art 230 inclusing no exceeding the ampacity of the incoming service conductors. I have to ask: Why not add a sixth disconnect to the panel ?

 

[infinity]

I was asking because the word tap has specific parameters that do not seem to apply to service entrance conductors.

240.2 Tap Conductors. As used in this article, a tap conductor is
defined as a conductor, other than a service conductor, that
has overcurrent protection ahead of its point of supply that
exceeds the value permitted for similar conductors that are
protected as described elsewhere in 240.4.

 

[augie47]

I was asking because the word tap has specific parameters that do not seem to apply to service entrance conductors.

and I fully understand and agree with you...thus my question, what do we call it ? In your opinion, is what he proposed allowable under the NEC ? So is it a "non 240tap" ? a rose is a rose

 

[Gregg Harris]

I was asking because the word tap has specific parameters that do not seem to apply to service entrance conductors.

What about

230.46 Spliced Conductors. Service-entrance conductors shall be permitted to be spliced or tapped in accordance with 110.14, 300.5(E), 300.13, and 300.15.

 

[Smart $]

What about

230.46 Spliced Conductors. Service-entrance conductors shall be permitted to be spliced or tapped in accordance with 110.14, 300.5(E), 300.13, and 300.15.

Exactly. Taps exist (or are permitted) outside the restriction of the Article 240 definition. For service conductors, I think it would simply mean the ampacity of the tap conductor is less than that of the tapped.

 

[hotline]

Service Tap

Thanks you augie47, infinity & Smart $

I greatly appreciate all the input on this topic.

To answer the question ?Why not add a sixth disconnect to the panel?? There is no sufficient bus space for a 200 amp switch.

I see that in ?230.46 Spliced Conductors? that we can make service entrance conductor splices. But I do not see where is allows for the under sizing of the conductors.

Would 350 Kcmil work as a tap or service extension in this case? Is there a not less than 1/3 or anything like that addressed?
The new switch at the end of the tap conductors would be 10 feet left of the MDP in the same room.

Thanks again for everyone?s help.

 

[Smart $]

...

I see that in “230.46 Spliced Conductors” that we can make service entrance conductor splices. But I do not see where is allows for the under sizing of the conductors.

Would 350 Kcmil work as a tap or service extension in this case? Is there a not less than 1/3 or anything like that addressed?
The new switch at the end of the tap conductors would be 10 feet left of the MDP in the same room.

...

Well, you can't "undersize"... but you can size for load and OCPD.

I can't say 350kcmil is suffcient because you have yet to indicate load, switch, ocp rating, or any other particulars which affect sizing. There is one minimum which must be met for the disconnect rating, but your situation takes you well above that minimum (speculating on your 350kcmil reference).

The six service diconnecting means you would end up with must be grouped. There is no set rule on distance for that grouping. 10' away will be at the discretion of the AHJ. If I were AHJ, I would not allow it.

 

[augie47]

As I see it your "non-tap" tap would be required to meet 230.70(A)(1), 230.72 & 240.4. In addition you would need to assure your added load does not cause an excess load to the ampacity of the existing conductors.